It is well-known that a magnetic field can be produced by employing various types of basic geometries, such as the Helmholz coil or the double Helmholz coil (Katsuji Kaminishi, Rev. Sci. Instrum. 52 (3) March 1981) or a solenoid compensated at its ends (Garrett, Journal of Applied Physics, vol. 40 p. 3171, July 1969) or separate solenoids. Generally, the manufacturing costs of such a coil arrangement are considered proportional to the product of power P spent as resistance losses in coils and a winding mass m, fulfilling the equation: EQU Pm=kd.sup.4 .multidot.B.sup.2,
wherein k is a proportionally factor depending on a selected geometry and winding material, d is a dimension describing the size of a magnet, primarily its diameter, and B is a produced field. It can be seen that the costs depend very much on the size of an apparatus. Thus, in view of the costs, it is preferable to make a magnetic coil as small as possible as long as it is considered that samples to be analysed or a target to be examined must be fitted inside a coil arrangement. On the other hand, it must be considered that eddy currents generated on the conductive surfaces of a coil arrangement producing a homogeneous basic magnetic field, especially in the body portions of a coil arrangement, disturb the operation of a radiofrequency transmitter-receiver coil or a so-called rf-coil as well as gradient coils. A result of this has been a necessity to make the basic coil arrangement 20 . . . 30% larger than an rf-coil and gradient coils which in practice has meant that the price of a coil arrangement has doubled or tripled.